Partners’ progress concerning the Heaven project (July 2021 – September 2022)


During the last year, Air Liquide (ALAT) has been manufacturing the LH2 tank and its control command box which can be filled with 16 kg of LH2. After the debugging and tuning phase, ALAT performed tests on this hardware with LH2, in particular safety chains, alarms, fuelling and defueling operations. These were validated for performances in normal cases, extremes cases and failure cases. These tests were held with partners’ attendees from H2Fly and PVS.

Team of the Heaven project with the cryogenic tank during LH2 acceptance tests on ALAT's tests facilities

Team of the Heaven project with the cryogenic tank during LH2 acceptance tests on ALAT’s tests facilities

After functional tests, a qualification test on a vibration test bench was successfully performed, verifying the LH2 tank can withstand mechanical loads of being used on board of H2FLY’s HY4 aircraft. ALAT also successfully tested a Ground Refueling Equipment’s ability to fill the tank with LH2 coming from a LH2 trailer.

The next step will be the ground tests on aircraft at Air Liquide Campus Technology Grenoble with H2FLY and PVS in the beginning of 2023.


After concluding the shortstack tests, necessary to develop an operation strategy for the NM5-Type EKPO PEM-Stack at only slightly elevated pressure levels (up to about 1.150 mbar), first system tests for operating the shortstack at higher pressures have been conducted. To be able to perform tests with cathode outlet pressures of up to 2,5 bar another recirculation pump was installed and some smaller modifications to the system became necessary.

With these modifications first tests could be conducted. The graph on the next page shows a preliminary test, showing operation at up to 2.300 hPa Cathode Pressure, archiving max. power output of 3,6 kW.


Stackcurrent, Cathodepressures and Stackpower during pressurized performance test

Stackcurrent, Cathodepressures and Stackpower during pressurized performance test


Going forward, H2FLY will be leading the HEAVEN project and overseeing all activities related to the integration and testing of the liquid hydrogen tank into the HY4. As such, H2FLY supplies the complete fuel cell and drivetrain system, along with the integration platform HY4 and the overall aircraft system architecture and controls. Being the owner of the HY4 aircraft and HEAVEN development lead, H2FLY holds a critical coordinative role, ensuring each of the system parts are properly adapted and can harmoniously function. As an example, the picture below shows the integrated liquid hydrogen tank of ALAT in the HY4 platform.

H2FLY’s responsibilities in the HEAVEN project cover the entire aircraft development process. H2FLY holds the leading role in defining and providing requirements to the HEAVEN consortium, regarding the design and adaption of aircraft parts and components. H2FLY further carried out critical work packages on the architectural level to meet the requirements of a liquid hydrogen system integration, such as a modification of the fuel cell system design and system architecture. Also, the buffer tank architecture has been designed and the components for coupling the buffer tank with the LH2 tank have been specified and procured as planned. Other essential and safety-relevant parts on board of the aircraft, for which H2FLY covered the design and development, were the adaption of the heating system of the liquid hydrogen, the provision of the complete telemetry system, and other critical parts of the hydrogen evacuation system.

As a critical element in all aircraft developments, H2FLY facilitates the safe integration of the liquid hydrogen tank into the HY4 and ensures safety throughout the anticipated flight test campaign. To this end, H2FLY has been performing extensive safety analyses regarding HY4 as well as flight operations, including constant alignment of safety requirements with the HEAVEN consortium. In preparation for the anticipated flight test campaign, coupling tests are scheduled in early 2023. H2FLYdelivered a start-up procedure for the drivetrain system and will provide necessary drivetrain modifications throughout the campaigns. Moreover, H2Fly delivered a test plan to ensure safe coupling-, ground-, and flight tests, and continues to update the plan in accordance with the HEAVEN consortium. Lastly, H2FLY will provide continued support to PVS in all activities related to the test flight campaign, as the company’s team has gathered crucial know-how in previous flight-testing campaigns of the hydrogen-powered HY4, and recently achieved a strong growth of its flight team.

Integration work is expected to be completed over the coming months. Following the integration of the new liquid hydrogen tank and fuel cells, the aircraft is planned to enter a rigorous programme of ground testing early in 2023 and is expected to be the world’s first commercial aircraft to fly using liquid hydrogen. In conclusion, all works of H2FLY in the HEAVEN project support the company’s leading vision of enabling emission-free, hydrogen-powered aviation and revolutionize air travel and will be further utilized in the company’s ongoing activity to scale the technology to regional turboprop level and CS-25 safety requirements.

ALAT's tank being mechanically integrated collaboratively by PVS and H2FLY into HY4 aircraft

ALAT’s tank being mechanically integrated collaboratively by PVS and H2FLY into HY4 aircraft


Pipistrel Vertical Solution’s (PVS) team, with the support of H2FLY, is leading the activities related to the mechanical integration of the tank components into the aircraft. This involved the design and execution of substantial modifications to parts of the left fuselage to house the tank whilst retaining the necessary structural integrity and at the same time providing the necessary space for all related subsystems, cabling and piping. The effort culminated in the first successful fitting trial of the actual liquid hydrogen tank into the aircraft at the Pipistrel facility in Ajdovščina, Slovenia.

Furthermore, common preparations for the flight test campaign have started, together with H2FLY as the aircraft owner, on both the administrative and organisational front. Communications with the Slovenian Civil Aviation Authority have started to obtain the necessary permit to perform flight tests, according to the requirements defined by H2FLY, on the modified aircraft. At the same time, the team is working towards identifying and dealing with all challenges related to operating with liquid hydrogen as aviation fuel together with the test airport personnel. This will include training all involved personnel, including rescue personnel, for dealing with liquid hydrogen.

Lastly, the preliminary design team has been bringing forward the activities related to the up-scaling of the technology for use in commercially relevant aircraft platforms, focussing on the development of modelling tools for the sizing and performance estimation of powerplant components that are crucial for the design of liquid hydrogen-powered aircraft.

In the next two months PVS, together with colleagues from H2FLY and ALAT, will be finalising the mechanical integration of the LH2 tank in light of the anticipated ground tests.


FUNDACION AYESA (FAY), as part of System integration and demonstration’s Total Cost of Ownership, has been working on the development of the platform to collect data in terms of economic information from each of the partners. This platform was released on April 7th. This one is only available for each of the Heaven partners through the corresponding user and password. Each of the partners only can visualize its own costs to maintain the confidentiality of its information.

This platform will be used to have an overview of the total cost of the system at different levels. FAY will analyse the provided costs to study the total cost of the ownership of the overall system.

Interview with Aleksander Gerbec, director of ECUBES Technology


Aleksander Gerbec is the director of ECUBES TECHNOLOGY, which is a clean energy technology firm developing new technologies and solutions enabling sector coupling and energy storage. By project development the company is supporting primarily proprietary technology integration by focusing on clean energy infrastructure and cross-sectoral power infrastructure integration. Their work also includes project development on resilience, civil and defence sectors by cross-sectoral infrastructure integration projects and services based on hydrogen technologies.

Q: What is the North Adriatic Hydrogen Valley?

A: The North Adriatic hydrogen valley (NAHV) is a project that clusters several industrial and research initiatives to carry out pilot projects across the complete hydrogen value chain (production, transport, distribution, and end use with storage and sector coupling). Present project consists of 34 consortia members with 19 investment projects and covers the aera show in the picture below. NAHV is unique compared to other Hydrogen valleys from the following prospects:

  • It is the first transnational hydrogen valley,
  • It is the first hydrogen Valley that is industry-driven, initiated as bottom-up approach, where industry from three territories has proposed projects and on November 24th, 2021 endorsement to support was given from three governments,
  • It has already received some investments from private companies before any public funding was available.

Q: What is the purpose of a hydrogen valley?

A: Hydrogen valleys are an important step towards locally integrated hydrogen ecosystems. They not only provide larger availability of sustainable energy but are also major drivers of industrial development and job creation. Although there are hurdles to overcome, the concept is spreading globally, spurred on by changing mindsets and growing private investment. Project North Adriatic hydrogen valley is the first step towards hydrogen ecosystem of North Adriatic and we believe that a fully integrated hydrogen ecosystem will be developed

Q: What are the advantages of transnational hydrogen valleys, compared to national hydrogen valleys?

A: Transnational hydrogen valleys are the marketplace for participants, who want to actively participate in the energy transition in the transnational territory. There they can develop their own projects and collaborate to establish an entire hydrogen value chain, which enables the flow of renewable energy in the transnational territory. Strong deployment of flexibility solutions is required to provide the power system with the ability to adapt to the dynamics of the residual load on all timescales: from frequency response to inter-year flexibility. This represents a huge challenge in energy transition and North Adriatic hydrogen valley is addressing solutions in this direction as well.

Q: How can companies in the aeronautical industry contribute to the establishment and development of hydrogen valleys?

A: All participants from the transport sector need to collaborate in order to achieve the most significant transition in the industry’s history – decarbonisation. The companies in the aeronautical industry could contribute by providing their user requirements for liquid hydrogen from infrastructure developers, governments, by promoting their use of hydrogen, by promoting the idea that clean air transport is already possible by use of clean hydrogen etc. Aeronautical companies can contribute also by becoming active participants in the market creation stage already, together with other front-runners.

Q: How can aeronautical companies benefit from being part of a hydrogen valley?

A: If aeronautical companies actively participate in the development of hydrogen ecosystems, then there is a higher probability that other developers, who are trying to develop hydrogen ecosystems, can succeed sooner, thus the entire region will benefit from the synergies and the end result. Companies can also guide infrastructure developers with their user requirements, helping to align project design accordingly and to get the required LH2 when they want it and to get it under affordable conditions. If they are active participants, they can get access to affordable liquid hydrogen much sooner than everyone else. Those who will be the first are expected to keep their position of frontrunners for a while, so everybody who sees interest in use of clean hydrogen should be actively involved in this regional approach. So – time for action is now – go ahead and require your supply of liquid hydrogen.

Relevant upcoming events about hydrogen, fuel cells and aviation

IQPC MEA Conference Seattle (15 – 17 November 2022):
More Electric Aircraft USA will bring together relevant stakeholders to ensure maximum knowledge transfer and professional exchange. During this full three-days-program with lectures and interactive workshops you will meet international experts from OEMs, suppliers, associations, and academia to discuss, hear and learn about their experiences and challenges in the fields of More Electric & Hybrid Aircraft.

Hydrogen Mobility Snap Summit (29 November 2022):
Our Mobility Snap Summit 2022 provides the forum for discussion and debate on the current climate within the mobility sector of the hydrogen community.

12th Aviation Forum Munich (05 – 06 December 2022):
Under the patronage of Airbus CPO Jürgen Westermeier, more than 800 decision-makers and experts from the aviation industry will meet at the Aviation Forum Munich. The group of participants consists of OEMs, manufacturers and suppliers at all tier levels, political decision-makers and thought leaders from Germany, Europe and worldwide.

Hannover Messe (17 – 21 April 2023):
HANNOVER MESSE is the most important international platform and hot spot for industrial transformation – with excellent innovations or unusual products. Here you will find all the facts that make one thing even clearer: participation is an absolute “must”!

Aero Friedrichshafen 2023 (19 – 22 April 2023, Friedrichshafen, Germany):
Discover what direction developments in the General Aviation industry are going at the AERO Friedrichshafen. With more than 600 exhibitors from 35 countries, 33,000 visitors and 600 journalists from all over the world, the AERO Friedrichshafen is the international community’s annual meeting place. At Lake Constance, numerous companies will be displaying their latest products and innovations, covering the whole industry from ultralights and gliders to business jets, helicopters and electric aircraft as well as avionics and maintenance.

Hydrogen Online Workshop 2023 (9-10 May 2023):
The Hydrogen Online Workshop (HOW) is a unique interactive event that provides a global platform for discussing the most important issues of the hydrogen industry. 150+ world-class experts in Keynotes and Workshops, interactive virtual Exhibition, 10000+ Hydrogen Pioneers, 110+ countries. The World’s Largest Interactive Hydrogen Event.

World Hydrogen Summit 2023 (9-11 May 2023):
The Sustainable Energy Council with partners the Port of Rotterdam, the City of Rotterdam and the Province of Zuid-Holland are delighted to renew their commitment to enhance the event as the official global springboard for hydrogen deals and project developments where real action is displayed to inspire and motivate the rest of the world. Welcoming 8000 decision makers, Energy Ministers, and CEOs from over 100 countries, it’s a truly global gathering of minds where key priorities are set, bold announcements are made, and new partnerships are forged.

Hydrogen Expo Italy (17-19 May 2023):
First Italian exhibition & conference entirely dedicated to the technological sector for the development of the hydrogen supply chain. The decarbonisation policy aimed at reducing global pollution sees hydrogen as a sustainable energy source since it can be generated using renewable energy and, therefore, it can be transported, stored and used as a gas; Italy can be an extremely interesting market for the development of hydrogen, thanks to the widespread presence of renewable energy sources and a capillary network for the transport of gas.

Paris Airshow (SIAE) (19 – 25 June 2023):
The 54th edition of the Show will take place at the Le Bourget Parc des Expositions in June 2023, and once again will bring together all the players in this global industry around the latest technological innovations. The first four days of the Show will be reserved for trade visitors, followed by three days open to the general public.